Wang Yu, Bai Xu, Hu Bo, Xing Maochen, Cao Qi, Ji Aiguo, Song Shuliang
Marine College, Shandong University, Weihai, Weihai 264209, China.
School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China.
Pharmaceutics. 2020 Feb 17;12(2):167. doi: 10.3390/pharmaceutics12020167.
Detailed knowledge of the intestinal transport of polymannuronic acid (PM) and polyguluronic acid (PG) is critical for understanding their biological activities. To investigate the transport in the gastrointestinal tract, PM and PG were chemically modified with tyramine and conjugated with fluorescein isothiocyanate (FITC) to synthesize FITC-PM (F-PM) and FITC-PG (F-PG) successfully. The transport mechanisms of F-PM and F-PG across the intestinal epithelial cell monolayers (Caco-2 cell monolayers) were then investigated. The results demonstrated that the transport of F-PM and F-PG into epithelial cells was time- and energy-dependent, which was mediated by the macropinocytosis pathway and the clathrin- and caveolae (or lipid raft)-mediated endocytic pathway. The transport process of F-PM and F-PG in Caco-2 cells depended on the acidification of endosomes and involved lysosomes. Tubulin mediated the transport of F-PM, but not of F-PG. Moreover, the absorption enhancer chitosan (CS) promoted the transport of F-PM and F-PG, increasing the apparent permeability coefficient (Papp) by 1.9-fold and 2.6-fold, respectively, by reversibly opening the tight junction (TJ). In summary, this study provided a comprehensive understanding of the transport of PM and PG in the small intestinal epithelial cells, which will provide a theoretical basis for the development of PM and PG with good intestinal absorption.
深入了解聚甘露糖醛酸（PM）和聚古洛糖醛酸（PG）的肠道转运对于理解它们的生物活性至关重要。为了研究其在胃肠道中的转运情况，将PM和PG用酪胺进行化学修饰，并与异硫氰酸荧光素（FITC）偶联，成功合成了FITC-PM（F-PM）和FITC-PG（F-PG）。随后研究了F-PM和F-PG跨肠上皮细胞单层（Caco-2细胞单层）的转运机制。结果表明，F-PM和F-PG进入上皮细胞的转运具有时间和能量依赖性，其由巨胞饮途径以及网格蛋白和小窝（或脂筏）介导的内吞途径介导。F-PM和F-PG在Caco-2细胞中的转运过程依赖于内体的酸化并涉及溶酶体。微管蛋白介导F-PM的转运，但不介导F-PG的转运。此外，吸收增强剂壳聚糖（CS）促进了F-PM和F-PG的转运，通过可逆地打开紧密连接（TJ），分别使表观渗透系数（Papp）提高了1.9倍和2.6倍。总之，本研究全面了解了PM和PG在小肠上皮细胞中的转运情况，这将为开发具有良好肠道吸收性的PM和PG提供理论依据。
